dasher



Feb. 1, 1955 P. J. DAsHER METHODS FOR RECLAIMING UNVULCANIZED RUB BERSCRAP. OR THE LIKE. CONTAINING FIBER BY TREATMENT WITH MINERAL ACIDVAPOR 3 Sheets-Sheet l Filed March 14, 1951 ..IRTN

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Feb. l, 1955 P. J DASHER 2,701,268

METHODS FOR RECLAIMING UNVULCANIZED RUBBER SCRAP. OR THE LIKE,CONTAINING FIBER BY TREATMENT WITH MINERAL ACID VAPOR r 5 t mh T e N s 0e T .n f f f f W B q v /U//// N S f /ff l t l ,f e J e Tn Z 3 U M a DI.V.. B

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Feb. 1, 1955 P. J. DASHER METHODS FOR RECLAIMING uNvULcANIzED RUBBERSCRAP. OR THE LIKE. CONTAINING FIBER BY TREATMENT WITH MINERAL ACIDVAPOR Filed March '14, 1951 UZON s NYON wUZON l`IN7O.N mun/ ON NUZONLIDO H Noud) United States arent ce 2,701,268 Patented Feb. 1, i955METHGDS FOR RECLAIMING UN VULCANIZED RUBBER SCRAP, OR THE LIKE,CONTAINING lllRBY TREATMENT WITH MINERAL ACID Paul J. Dasher,Willoughby, Ohio, assigner to Dasher Rubber and Chemical Company,Fairport Harbor, Ohio, a corporation of Ohio Application March 14, 1951,Serial No. 215,495

7 Claims. (Cl. 260-711) met with widespread or continued commercialsuccess,

and none of these methods are employed today in the rubber industry, forexample, in order to salvage or reclaim rubber from scrap includingvegetable and like fibers. The lack of use of known acid-treatingtechniques in the rubber industry exists in spite of the fact that many,

many tons of vegetable fiber-containing, unvulcanized rubber scrapresults every day in the manufacture of various friction-containingrubber products, such as tires, mechanical goods, V-belts, and boots andshoes.

It is my opinion that the rubber industry, which, from time to time, hastried to render commercially practical acid vapor treating techniquesfor removing vegetable fibers, has finally discarded all known methodsas impractical and unsatisfactory because of expense of treatment,difficulty of maintaining treatment conditions uniform, lack ofcompleteness of treatment, that is, lack of removal of all vegetablefibers, expense of maintenance of equipment, and lack of maintenance ofproper operating conditions, and specifically temperatures, duringtreatment.

Of course, the rubber industry does employ successfully rubberreclaiming processes of the alkali type on vulcanized rubber whichreconditions the vulcanized rubber to a semi-unvulcanized state, forexample, so that it can be mixed with unvulcanizcd rubber, compounded,and subsequently vulcanized. These known reclaiming operations onvulcanized rubber are often performed upon rubber containing vegetablefibers, with the fibers being converted to ash, which is usually washedout of the reclaimed rubber. These successful alkali processes forreclaiming vulcanized rubber should not be confused with the acid vapormethods of the present invention and those discussed above of the priorart for reclaiming unvulcanized rubber scrap, and, particularly, theremoval of vegetable bers therefrom.

lt is the general object of my invention to avoid and overcome theforegoing and other difiiculties of and objections to known methods andapparatus for reclaiming unvulcanized rubber containing fabric by theprovision of improved inexpensive, readily handled apparatus and methodsfor commercially and in production quantities reclaiming unvulcanizedrubber, and the like, and for removing vegetable fibers, such as rayonand cotton.

Another object of my invention is to provide substantially automaticapparatus of relatively inexpensive character for rapidly andcontinuously, and with a minimum of supervision, removing vegetablefiber from unvulcanized rubber.

Another object of my invention is the provision of sirnpliiied andimproved methods for removing vegetable fiber from unvulcanized rubber,or the like, and wherein the treating method is continuous and with therubber scrap being at all times during the treating process at atemperature definitely below a temperature which would injure it.

Another object of my invention is the provision of an improved methodand apparatus for recovering acid after the scrap treating process.

Another object of my invention is to provide methods for treating rubberscrap, and the like, in which the acid vapor employed in the treatingprocess is derived from a water solution of the acid gas in aconcentration such that when the acid vapor engages the scrap, it willhave a dehydrating effect on the scrap and with the resulting acid gasand water vapor in contact with the scrap being substantially constantboiling in character, i. e., in the neighborhood of 20.2% acid gaspresent.

Another object of my invention is the provision of a treating process ofthe character described wherein the temperature of the scrap and of theacid vapor is carefully controlled along a treating path to create aseries of separate zones which blend one into the other, and with thetemperature of the stock at all times being kept below the temperatureof the acid vapor.

Another object of my invention is to provide a treating process of thegeneral type referred to above in which the heat at the end of thetreating path where the vapor first engages the scrap is relatively highto create a drying zone, the heat then gradually dropping off as thevapor moves along the path to create a fabric-reacting zone and anabsorption zone, and then the heat building back up during the lastportion of the travel of the gas over the scrap to substantially thetemperature of the drying zone to create a re-evaporation zone.

Another object of my invention is to provide apparatus for the processesand methods described and wherein adjustments can be readily made tocontrol factors of time of reaction, temperature, and concentrationwhereby quality production reclaiming is consistently achieved.

The foregoing objects of my invention, and other objects which willbecome apparent as the description proceeds, are achieved by passing thebroken-up scrap along an elongated path while agitating the scrap,passing a mineral-acid vapor usually in the opposite direction over thescrap during its travel along the path, maintaining the vapor at atemperature higher than the temperature of the scrap during the passageof the scrap along the path, and applying controlled heat around thepath of travel of the vapor and scrap. Usually the heat applied ishigher at both ends of the path than in the middle thereof. Also, thefinishing temperature of the scrap is never above about 175 eF.Preferably a mineral acid is employed, and specifically hydrochloricacid, and I employ a concentration of between about 21% to about 28% HC1gas so that when the acid vapor engages the scrap, the amount of waterpresent in the scrap will join with the acid vapor to result in an acidvapor having substantially a constant boiling point, i. c., aconcentration of substantially 20.2% HCl in the water which, in liquidform, boils at a constant boiling point of 110 C.

In the apparatus of the invention, I employ an acidresistant tube whichis journaiied for rotation about its own axis, usually at a selectivelyvariable speed, and with the tube being preferably adjustably supportedat a selected angle with the horizontal. Vapor supply means areconnected to the lower end of the tube, and the acid vapor is drawn outthe upper end of the tube with jetscrubbing means, or the like, forapplying a sucking action to the tube. Scrap supply means are connectedto the upper end of the tube and may include centrifugal feed means. Thetube carries vanes for agitating the scrap as it moves down the tube,and the entire tube is surrounded by an insulating hood. A plurality ofindependently controllable heating elements are positioned between thehood and tube for establishing a plurality of heat zones along thelength of the tube. Acid recovery means are provided for salvaging asmuch of the treating acid as possible.

For a better understanding of my invention, reference should be had tothe accompanying drawings, wherein:

Fig. l is a schematic layout of one typical embodiment of the apparatusof my invention in its entirety and capable of performing the improvedmethod of my invention;

Fig. 2 is a side elevation, partially broken away, of the processingtube forming a part of my invention;

Fig. 3 is a vertical transverse cross-sectional view of the processingtube of Fig. 2, and taken substantially on line III-III of Fig. 2, andon a slightly larger scale;

Fig. 4 is an end view of the processing tube, taken substantially onii'ne IV-V of Fig. 2, and on a slightly larger scale;

Fig. 5 is a fragmentary sectional view taken on line V-V of Fig. 2 andillustrating details of the centrifugal feed. means for the scrap;

Fig. 6 is an enlarged fragmentary sectional view taken substantially online VI-Vl of Fig. 2 and showing a labyrinth seal at one end of theprocessing tube;

Fig. 7 is a diagrammatic illustration of the processing tube of Fig. 2,and illustrating the controlled heat zones thereof; and

Fig. 8 is a graphical representation of the treating temperatures in thevarious zones of Fig. 7, and likewise, Fig. 8 supplies additionalinformation as to the temperatures of the acid vapor and the scrap.

'The principles of my invention are broadly applicable to the removal.of cellulose from plastic in any of a variety of for-ms, but arespecifically adapted to the removal of vegetable fiber from unvulcanizedrubber scrap. For purposes of simplification, the invention will bedescribed 1n coniunction with operations upon rubber, but the scope otf:h invention is not to be so limited unless specifically s a e In thedrawings, and having particular reference to Fig. l, the numeral 104indicates a plurality of storage compartments or bins for receivingrubber scrap or other similar materials to be reclaimed, and from thestorage bins the rubber travels by conveyor, truck, or the like, to abale-cutter 12 which cuts the scrap into blocks of a size which can beconveniently handled. The blocks of scrap travel by suitable conveyor orhand truck to one or more cracker mills 14 of known type and characterwhich break up the blocks of scrap into rough, coarse sheets, which inturn are conveyed or otherwise carried to rotary knife cutters 16` Therotary knife cutters 16 are preferably employed 1n pairs, two cuttersbeing positioned at right angles to each other in the manner shown inFig. l so that a rough sheet of scrap fed into the first cutter resultsin the sheet being cut into a plurality of narrow strips which then passto the second cutter at 90 so that the strips are cut into small pieces.In fact, the scrap should be broken up by the process described so thatall particles of the scrap will now pass through approximately a screen.This breaking up or comminuting of the scrap to relatively smallparticle size insures that the vegetable fibers or fabric embedded inthe scrap are exposed at least at their ends on one or more surfaces ofthe scrap lwith no piece of the scrap or of the vegetable fibers beingvery long whereby the vegetable fibers are adequately exposed to attackby the acid vapors, as hereinafter described.

From the rotary knife cutters 16, the broken-up scrap is passed, usuallyby an air conveyor 18, to a storage bin 20. Preferably this storage bin20 is of the cyclone or blower type so that, should any light pieces ofthe fabric have been mechanically removed from the rubber by thepreviously described treating process, these portions of fabric will beseparated and removed from the rubber scrap by the cyclone storage bin.

The rubber scrap is fed from the storage bin 20. often by gravity andwith the aid of a centrifugal feeding means to be hereinafter described,to a processing tube, indi cated as a whole by the numeral 22. Thisprocessing tube will be described in detail hereinafter together withthe method performed therein. Sutiice it to say here that the rubberscrap moves through the processing tube 22 to a hammer mill 24 whichserves to break up and mechanically separate the rubber scrap from thefabric which has been attacked by the acid vapors in the processing tube22. From the hammer mill 24. the rubber scrap passes to a screen 26which is vibrated to separate out and discard objectionably largeparticles of scrap. The material then passes to the cyclone-separator30. of known construction, which centrifugally and with the aid of airYseparates the reiined scrap from the hydrolized fabric or fiber,separate conduits receiving the refined scrap and the hydrolized fiber.The fiber is salvaged as well as the scrap and can be used as a tillerfor rubber or plastic or as cellulose having a long chain length.

It will be understood that acid vapor is passed through the processingtube 22, preferably in a direction opposite toithe flow of scraptherethrough, and the acid vapor is obtained from acid carried in astorage tank 32 from which it is lifted by a pump 34, passed throughsuitable indicating means, such Aas va gravity indicator 36 and a owmeter 38, to a vaporizer or boiler 40, from which the acid vapor isconducted by a suitable acid-resisting pipe to the tube 22.

From the processing tube 22, the acid vapor is withdrawn usually bysuction and by a conduit 41 of acidresistant type to a condenser 42which condenses a large proportion of the acid and water vapor back toliquid acid which flows back to the storage tank 32 by way of conduit43. Any uncondensed vapor passes to a cyclone separator 44 which removesany fabric that might be pulled into the separator, such materialpassing to a storage tank 46. Fume scrubbers 48 of the jet type draw theremaining acid vapor from the separator 44 into separating boxes 50 andsimultaneously condense the vapor. the condensed liquid flowing byconduit 52 back to the acid storage tank 32. The fume scrubbers 48 and.separating boxes 50 are connected in series in the manner illustrated toinsure that no acid vapor fumes escape into the atmosphere. Conduit 42and separate 44 may be insulated to help avoid condensation except atthe condenser 42. An unusual feature of the action of the fume scrubbers48 is that these are driven in their jet action by liquid acid .takenfrom the storage tank 32 by pump 49 and conduit 51. Also, it might benoted here that instead of drawing the acid vapor with a suction actionthrough the processing tube 22, I may -use a forced .draft with a owerfan or fans.

Referring now to Figures 7 and 8 of the drawings, and particularlyconsidering the improved reclaiming method of my invention, Fig. 7diagrammatically illustrates the travel of the scrap along an elongatedpath provided by the processing tube 22, and with the acid vaporprefererably moving through the tube in a direction opposite to thetravel of the stock. I have divided Imy processing tube into a series ofeight zones and independently and individually control the temperatureof each one of the eight zones so as to obtain an exact control oftemperature during the treating process. Zones 1 and 2 comprise are-evaporation zone; zones 3, 4, and 5 constitute an absorption zone;zones 6 and 7 comprise a cellulosereacting zone; and zone 8, a dryingzone.

Now looking at the graph of Fig. 8, the zone of travel is shown as theabscissa, the ordinate is shown in terms of zone thermostat temperaturein degrees Fahrenheit. The resulting curves are, respectively, a solidline showing the zone temperatures for the treatment of tires andmechanical goods scrap, the chain-dotted line for boot and shoe scrap,and the dotted line for V-belt scrap. It will be noted that the solidline curve in Fig. 8 shows a teniperature in zone 1 of approximately 325F., this graditally dropping down to a temperature of about 250 F. inzones 4 and 5, and building back up to a temperature in zones 7 and 8 ofsomewhat over 300 F. and usually in the neighborhood of 325 F. Boot andshoe scrap treatment involves zone temperatures which are down some 30F. or so from the zone temperatures used for treating tires andmechanical goods scrap, for example, a temperature in zone 1 of about290 F. gradually decreasing to zones 4 and 5 to a temperature of about210 F. and building back up to a temperature of about 290 F. in zones 7and 8, all as indicated by the chaindotted line. The dotted linerepresenting the zone temperatures for the treatment of V-belt scrap,unusually high in rubber, is some 10 F. to 15 F. lower than the zonetemperatures for the treating of boot and shoe scrap` and involves, forexample, about a 275 F. temperature in zone 1 gradually reducing to atemperature of about 200 F. in zones 4 and 5, and building back up toabout a 275 F. temperature in zones 7 and 8.

Fig. 8 is also of interest in illustrating that the starting temperatureof .the scrap in zone 1 is from about 90 F. to about F., and during thepassage of the scrap through the processing tube, the temperature of thestock gradually climbs until the finishing temperature of the stock isas shown, namely. about 175 F. maximum for scrap from tires andmechanical goods. about 150 F. maximum for boot and shoe scrap. andabout F. maximum for V-belt scrap. Fig. 8 also illustrates that thestarting temperature of the acid vapor is between about 200 F. :andabout v240" F., and the tinishirig tenipgp-)ange .of the vapor isbetween about F. and about Several important characteristics of myimproved proc f substantially constant boiling'point concentration.

ess reveal themselves from a study of Figures 7 and 8. In the firstplace, it becomes evident that in my process the scrap being treated isalways at a temperature less than the temperature of the acid vaporemployed to treat the scrap. This is important for the reason that theacid vapor tends to condense on the stock, and allows the stock to betreated at a minimum temperature to thereby avoid burning orvulcanization of the rubber of the scrap while insuring the maximum ofchemical action upon the cellulose tibers of the scrap. It should benoted here that the action of the acid vapor upon the fibers is one ofhydrolysis in which two chemical reactions compete. The first of thesereactions is merely the de-polymerization (shortening of chain length)of the cellulose molecule. The second reaction is the actual hydrolysisof the cellulose molecule to sugar, which is objectionable from areclaim standpoint. By keeping the temperature on the cellulose low asabove described, I am able to confine the treatment of the celluloselargely to the first reaction described, without the second reactionever getting a chance -to get really started.

A particularly important part of the action described in the precedingparagraph is effected by the use of a mineral acid, and specificallyhydrochloric acid of a concentration between about 21% and about 28%. Itis known, of course, that hydrochloric acid of a HC1 concentration of20.2% is constant boiling' in character, boiling about 110 C., and theacid vapor contains substantially the same percentage of HC1 as theliquid acid. When hydrochloric acid is concentrated up to contain thelimit of about 39% HC1, the' boiling point is lowered and the acid vaporis largely HC1. At least certain of the advantages of my invention canbe achieved by using HC1 gas alone, as, for example, in the treatment ofvery wet scrap within the limits of the results to be achieved asdiscussed in the following paragraph.

I have discovered that using an acid concentration of between about 21%and about 28% HC1, and usually in the neighborhood of about 25% HC1, Iobtain a very definite drying and dehydrating action upon the rubberscrap being treated. Ordinarily there is a considerable amount of waterpresent in the scrap, for example, on an average about 8 pounds of Waterin 100 pounds of scrap, and When I employ an acid having a concentrationwithin the limits specified, then the acid vapor ends up on the scrapatIa n other words, the acid vapor absorbs the water present in thescrap, and this additional water in the acid vapor brings the HClconcentration to approximately the 20.2% HC1, namely, that of a constantboiling point mixture. Thus, the processing tube acts as a drying tube,and allows the scrap to be run at a lower temperature than with otherknown processes. It will be understood that in treating scrap having ahigh water content, for example, more than 8 pounds of water to 100pounds of scrap, then I use an acid having a concentration up towards28% HC1, and in treating a scrap having a low water content, I use anacid having a concentration of down towards 21% HC1.

I have likewise discovered that it is sometimes advantageous, forexample, when working with difficult scrap, to employ a wetting agent onthe scrap prior to treatment with the acid vapor. I have found wettingagents satisfactory which are selected from the polar groups, such asamines and sulfonates which are active in highly concentrated acidsolutions and which are stable for at least one minute at a temperaturenot to exceed 225 F. I employ a wetting agent of the type indicated andin an amount of about .05 of 1% of the weight of the scrap and spray thewetting agent on the scrap in the cracker mill or at some point beforethe scrap passes to the treating tube. The wetting agent improves thecondensing action of the acid vapor on the scrap and the acid action inpenetrating up the cords of the fabric in the scrap is enhanced.

Another important criterion in my improved reclaiming process is theratio of the total volume of acid gas to the total volume of scrap.Stated more specifically, to one volume of scrap, which runs about 20pounds per cubic foot bulk density, I use at least about 8 volumes ofacid gas. From a practical standpoint, I may use up to about 20 volumesof acid gas, and greater amounts than this usually merely serve toprovide an excess of gas which, except for increasing the drying effecton the scrap, serves no useful purpose. Still more specifically, in atypical days run, I employed 113 gallons of acid to treat about 24,000poundsof stock. From a practical operative standpoint, the limits shouldbe suchthat. the acid gas volume used is suicient to adequately performthe treating action on the ber content of any given scrap being treated.

Having reference now to Figures 2 to 6 of the drawings, the numeral 22indicates generally the processing tube to which are secured at spacedpoints along its length a plurality of bearing rings which rotatablyengage and are supported onI cradle-forming rollers 62 carried on a baseframe 64 which extends the full length of the tube and somewhat beyondthe tube on each end. The base frame 64 is pivotally supported at oneend, as at 66, and at the other end is adjustably supported by anysuitable means, typical means being shown at 68, whereby one end of theframe can be vertically adjusted to control the inclination of thelongitudinal axis of the tube 22 with the horizontal. Usually the angleof the tube 22 with the horizontal is between about 4 and about 8, beinggen.` erally in the neighborhood of 5 to 6.

Means are provided for rotating the tube 22 about its longitudinal axis,and such means may comprise a ring gear secured to the' tube, this gearbeing engaged by a pinion gear 72 extending from a speed changer 74driven by a motor 76. Of course, a variable speed motor may be utilizedwith or without gear reduction, and the rotation of the tube 22 can beadjusted to any one of a series of rotations per minute, for example,14, 17, 28, or 55. A thrust bearing is associated with at least one setof cradle rollers 62 to take up end thrust on the tube 22. Also, thetube 22, as best seen in Figures 3 and 7, is provided with a pluralityof longitudinally extending vanes 82 for assisting in agitating andtumbling the scrap as i-t passes along the length of the tube duringtreatment.

The upper end of the tube 22, as viewed in Fig. 2, is adapted toreceivel the scrap which is supplied thereto by way of a conduit 84which extends to a centrifugal feeding means 86. As seen in Fig. 5,these feeding means 86 include a disc 88 carrying a plurality ofimpeller blades 90, the scrap being usually gravity fed to the center ofthe impeller blades and being thrown out centrifugally as the disc 88 isdriven from a shaft 92 by suitable motor means (not shown). Thecentrifugal feed mechanism 86 is carried on an end frame 94 secured tothe base frame 64, and the centrifugal feed means 86 includes a roundplate v 96 having an opening cut therethrough to receive the disc 88 andimpeller blades 90 of the centrifugal feed means, the casing 98 of thecentrifugal feed means being welded or otherwise joined to the openingin the plate 96.

The plate 96 and the centrifugal feed means 86 are mounted for movementtoward and from the end of the tube 22.. This is accomplished by theprovision of bolts 100 which are secured to the plate 96, and whichextend through holes in the end frame 94. Compression springs 102 on thebolts hold the plate 96 in close proximity to the end of the tube 22 andthe nuts on the bolts 100 are adjusted to insure that the clearancebetween the disc 96 and the end of the tube is kept at a minimum. Aconduit 104 is connected to the plate 96 and provides for exhausting theacid vapor from the upper end of the tube 22.

At the lower end of the tube 22, I provide a short tubular portion whichis rigidly held by angles 112 on the base frame 64. A labyrinth seal, asbest seen in Fig. 6, is provided between the tubular portion 110 and theend of the tube 22 by means of a liange 114 secured to the tube. Aconduit 116 provides for the introduction of acid vapor into the tube22, and the tubular portion 110 is provided with an opening near itsbottom so that scrap moving down through the tube 22 is discharged outof the opening and is conveyed away from the processing tube 22, forexample, by means of a conveyor belt 118.

It will be understood that the processing tube 22, and the various partsassociated therewith and any conduits conducting the acid or acid vaporare made from acidresistant material of any suitable type. I have foundthat Hastelloy B, an acid-resistant stainless steel alloy, is generallysatisfactory.

Looking now at Figures 2 and 3, an important part of the processing tube22 is the careful control of heat along the full length of the tube andin the various zoneshereinbefore described. This I achieve bysurrounding the tube 22 with a heat-insulating hood or cover 122, madeof any suitable heat-resistant insulation, and constructed substantiallyin the form illustrated in Fig. 3 to surround the tops, sides, andbottom. of the tube 22 over its entire length. The vheat-insulating hood122is of a size so that heaters 124 can be positioned between the sidesof the hood and the tube 22, an independently controlled heater beingassociated with each of the various zones particularly illustrated inFig. 7 of the drawings. Preferably the heaters 124 are electrical incharacter, and are arranged to be individually controlled so as toprovide the heat specified in Fig. 8. A thermostat 126 is provided ineach zone, and as shown in Fig. 3, is conveniently positioned in closeproximity to the outer periphery of the tube 22, and it is thetemperature at this point {vhicl is referred to in the curves andtemperature of In the operation of my improved process, it will beunderstood that three variables are of particular importance. These arethe concentration of the acid vapor used in the treatment, thetemperature maintained during the treatment, and the length of time ofthe treatment. I have already discussed the acid concentrations, and thetemperature of treatment. Insofar as the length of time of the treatmentis concerned, it will be recognzed that increasing the angle ofinclination of the processing tube 22, and the speed of rotation of thetube 22, will reduce the treatment time. With acid concentrations andtreating temperatures as described, the speed of rotation of the tubeand the angle of inclination to the horizontal are adjusted so that thetotal length of treating time of the scrap is between about two andabout six minutes, and is usually in the neighborhood of four to veminutes.

It may be observed that, insofar as time of treatment is concerned, withlarger size material, for example, material towards or above the 3/8"particle size, the material moves more quickly through the treating tubewith the tube angle and R. P. M. the same. Thus, with treatment onlarger particle size and because of the necessity for the gas vapor topenetrate further into the larger particles, the tube angle should bedecreased, or the R. P. M. of the tube should be decreased, or the gasvapor volume should be increased. With smaller particles of materialtowards for example, the converse of the above is true.

Also, the volume of gas flow should be maintained as slow as possible toallow for the greatest penetration of the vapor into the fiber of thematerial, and to avoid the pulling of fiber iiuff out of the tube, whichis called dusting.

From the foregoing, it will be recognized that the various objects of myinvention have been achieved by the provision of improved methods andapparatus for oxidizing cellulose or other vegetable fibers or fabricout of plastic scrap and particularly rubber scrap. The temperatureutilized in the reclaiming process is sufficiently low so that the scrapitself is not oxidized or burnt. The treating processes can bemaintained uniform over long treating periods, and can be utilized tosatisfactorily reclaim scrap in production quantities. Thus, my improvedi process is characterized by high efiiciency and relatively low cost,as is the treating apparatus of my invention.

Throughout the description, I have referred to the fact that Ipreferably pass the acid vapor over scrap in a direction opposite to thedirection of movement of the scrap. Although this counter ow movementhas distinct advantages, it is possible to pass the acid vapor over thescrap in the same direction as the scrap is moving.

Reference has also been made to the treatment of unvulcanized rubber andlike plastic. However, the principles of my invention can be used toremove fiber from vulcanized rubber and the like. Also, I can separatecotton from wool and cotton from nylon. In general, I can remove anymaterial which is attacked and hydrolized rather easily from anymaterial which is not readily attacked and hydrolized by the acid vapor.

While, in accord with the Patent Statutes, I have speciicallyillustrated and described one best known embodiment of my invention, itis to be particularly understood that I am not to be limited thereto orthereby, but that the scope of my invention is defined in the appendedclaims.

I claim:

l. That method of reclaiming both cellulose ber and rubber from built upfiber and rubber material which includes the steps of comminuting thematerial to substantially pass a 3A mesh screen, treating the materialhaving a water content of at least 1% with the vapor of hydrochloricacid having a concentration of between 21% temperature of the materialand about 28% HC1, the concentration of the entering HC1 beingmaintained greater than the cencentration of HCl in a constant boilingmixture and such that when the acid vapor mixes with the water presentin the material the resultant acid acting on the cellulose of thematerial approaches that of a constant boiling mixture maintaining theentering temperature of the acid vapor between about 200 and about 240F., bringing the temperature of the material during treatment fromapproximately room temperature up to a finishing temperature of betweenabout to about 175 F., agitating the material in the vapor, the totalvolume of the acid vapor being between about 8 to about 20 times thevolume of the material, continuing the treatment between about 2 andabout 7 minutes, removing the material, further reducing the material inparticle size, and separating the fiber from the rubber material.

2. That method of removing cellulose iiber from structural combinationswith non-cellulosic plastic material which includes the steps ofbreaking up the material to relatively small particle size, treating thematerial having a water content of at least 1% with the vapor ofhydrochloric acid having a concentration of between about 21% and about28% HC1, the concentration of the entering HCl being maintained greaterthan the concentration of HCl in a constant boiling mixture and suchthat when the acid vapor mixes with the water present in the materialthe resultant acid acting on the cellulose of the material approachesthat of a constant boiling mixture maintaining the temperature of theacid vapor at the start of the treatment between about 200 and about 240F., this temperature gradually being dropped until at the end of thetreatment the temperature is between about and about 180 F., bringingthe temperature of the material during treatment from room temperatureup to a finishing temperature of between about 125 to about F.,agitating the material in the vapor during treatment, the total volumeof the acid vapor during treatment being between about 8 to about 20times the volume of the material treated, continuing the treatmentbetween about 2 and about 7 minutes, removing the material, andseparating the liber from the material.

3. That method of reclaiming both cellulose liber and rubber from builtup fiber and rubber material which includes the steps of comminuting thematerial to substantially pass a mesh screen, treating the materialhaving a water content of at least 1% with the vapor of hydrochloricacid having a concentration of between 21% and about 28% HCl, theconcentration of the entering HCl being maintained greater than theconcentration of HC1 in a constant boiling mixture and such that whenthe acid vapor mixes with the water present in the material theresultant acid acting on the cellulose of the material approaches thatof a constant boiling mixture maintaining the entering temperature ofthe acid vapor between about 200 and 240 F., bringing the duringtreatment from approximately room temperature up to a finishingtemperature of between about 125 to about 175 F., agitating the materialin the vapor, the total volume of the acid vapor being between about 8to about 20 times the volume of the material, and separating the berfrom the rubber material.

4. That method of removing cellulose liber from structural combinationswith non-cellulosic plastic material which includes the steps ofbreaking up the material to relatively small particle size, treating thematerial having a water content of at least 1% with the vapor ofhydrochloric acid having a concentration of between about 21% and about28% HCl, the concentration of the entering HCl being maintained greaterthan the concentration of HCl in a constant boiling mixture and suchthat when the acid vapor mixes with the water present in the materialthe resultant acid acting on the cellulose of the material approachesthat of a constant boiling mixture maintaining the temperature of theacid vapor at the start of the treatment between about 200 and about 240F., this temperature gradually being dropped until at the end of thetreatment the temperature is between about 150 and about 180 F.,bringing the temperature of the material during treatment from roomtemperature up to a finishing temperature of between about 125 to about175 F., agitating the 'material in the vapor during treatment, removingthe material from the vapor, and physically separating the ber from thematerial.

5. That method of reclaiming cellulose fiber and plastic from scrapcombinations thereof which includes the steps of comminuting the scrap,treating the scrap with hydrochloric acid vapor made by boiling anaqueous solution of HCl having an HC1 concentration greater than that ofa constant boiling mixture and such that when the acid vapor mixes withthe water present in the scrap, the HCl concentration present in thecondensed vapor on the scrap is substantially that of a constant boilingmixture, maintaining the temperature of the scrap during treatment belowthe temperature of the acid vapor, and continuing the treatment for alength of time to effect substantially a maximum of depolymerization ofthe fiber while preventing actual hydrolysis of the cellulose moleculesof the ber to sugar.

6. That method of recovering the fabric and rubber from fabricreinforced rubber scrap, which includes the steps of passing thebroken-up scrap along an elongated -path while agitating the scrap,passing a mineral acid vapor in the opposite direction over the scrapduring its travel along the path, maintaining the vapor at aternperature higher than the temperature of the scrap during the passageof the scrap along the path, and applying heat around the path ot travelof the vapor and scrap, the heat at the end of the path where the vaporrst engages the scrap being relatively high to create a drying zone, theheat then gradually dropping o as the vapor moves along the path tocreate a fabric reacting zone and an absorption zone, the heat thenbuilding back up during the last portion of the travel of the vapor overthe scrap to substantially the temperature of the drying zone to createa re-evaporization zone.

7. That method of removing cellulose from scrap material which includesthe steps of treating the scrap with hydrochloric acid vapor made byboiling an aqueous solution of HCl having an HC1 concentration greaterthan that of a constant boiling mixture and such that when the acidvapor mixes with the water present in the scrap, the HCl concentrationin the vapor condensed on the scrap is substantially that of a constantboiling mixture, and continuing the treatment of the scrap as describeduntil substantial hydrolysis of the cellulose occurs.

References Cited in the tile of this patent UNITED STATES PATENTS1,680,915 Rose Aug. 14, 1928 2,304,548 Dasher Dec. 8, 1942 2,313,146Hirschberger Mar. 9, 1943 2,331,836 Hirschberger Oct. 12, 1943 2,487,666Navone Nov. 8, 1949 2,498,398 Dasher Feb. 21, 1950 2,543,315 FarregatFeb. 27, 1951 2,567,802 Carr et al Sept. 11, 1951

5. THAT METHOD OF RECLAIMING CELLULOSE FIBER AND PLASTIC FROM SCRAPCOMBINATIONS THEREOF WHICH INCLUDES THE STEPS OF COMMINUTING THE SCRAP,TREATING THE SCRAP WITH HYDROCHLORIC ACID VAPOR MADE BY BOILING ANAQUEOUS SOLUTION OF HC1 HAVING AN HC1 CONCENTRATION GREATER THAN THAT OFA CONSTANT BOILING MIXTURE AND SUCH THAT WHEN THE ACID VAPOR MIXES WITHTHE WATER PRESENT IN THE SCRAP, THE HC1 CONCENTRATION PRESENT IN THECONDENSED VAPOR ON THE SCRAP IS SUBSTANTIALLY THAT OF A CONSTANT BOILING